The challenger bank saw statutory profit more than double from £4.7m to £10m in the three months to September 30.
On an underlying basis, pre-tax profit came in at £15.1m, up from £7.2m in the same period last year.
Metro said in the first nine months of 2018 it delivered double-digit growth in deposits and record lending growth year-on-year.
The group said that, for the fourth successive quarter, it exceeded £1bn in net lending.
Total deposits increased to £14.8bn up from £10.8bn at the same time in 2017.
Boss Craig Donaldson said: “The first nine months of 2018 show another strong performance from Metro Bank.
“Our integrated, frictionless model - stores, online, mobile and phone - combined with superior service is a winning formula for our customers.
“We have continued to invest in our mobile services and have harnessed the power of Artificial Intelligence.”
However, Metro’s net interest margin - the difference between the interest received from borrowers and the amount paid out on deposits - fell from 1.94 per cent to 1.77 per cent.
The lender pinned the blame on competition in residential mortgages.